Notes on Family: Coronaviridae

enveloped spheres
enveloped spheres


General Description

This family is grouped with the Arteriviridae, Mesoniviridae and Roniviridae to form the order Nidovirales. All members of the order have enveloped particles containing a single species of single-stranded RNA that encodes for a number of proteins by means of a series of nested (Latin Nido = nest) subgenomic RNAs. The family Coronaviridae contains those members with spherical or pleomorphic virions more than 100nm in diameter (those of the family Arteriviridae are only 45-60nm) and which infect vertebrates. The family Roniviridae consists of viruses with bacilliform particles that infect crustaceans.


Virions enveloped and spherical or pleomorphic 120-160 nm in diameter.


Monopartite positive sense single-stranded RNA of size >20kb and with a 3'-polyA tail. Two large, overlapping ORFs at the 5'-end of the genome encode the major non-structural proteins and are expressed as a fusion protein by ribosomal frameshift. Downstream are up to 9 other genes, mostly or entirely encoding structural proteins, and these are expressed from a 3'-coterminal nested set of subgenomic RNAs.

Genera in the Family

  • Subfamily Coronavirinae: virions spherical with club-shaped projections and a core shell. Genera form distinct monophyletic groups:

  • Subfamily Torovirinae: virions pleomorphic without a core shell; tubular nuclecapsid with helical symmetry. Genera form distinct monophyletic groups and have different types of host: